A little background first.
Internet connection: Cable (Time Warner Road Runner)
Router: Linksys WRT54G
Issue: When downloading larger files, say my laptop updating World of Warcraft, all other PC connectivity slows down tremendously. My main PC, which is connected via a wired connection, slows to a crawl to load web pages while the laptop is downloading. Also, if I were to be downloading a torrent of the latest version of Ubuntu on my PC, any other attempts to surf while the download is happening is slow as well.
Is this an issue at the router, or my connection? I would hope my connection would be fast enough to handle downloading some files while surfing the internet. Are there steps I can take to pinpoint where the bottleneck is?